Method for fabricating display device and display device

ABSTRACT

A method for fabricating a display device includes forming a thin film transistor on a base substrate, forming a first electrode connected to the thin film transistor, forming a pixel defining layer overlapping a portion of the first electrode, such that the pixel defining layer exposes a portion of the first electrode and partitions pixel areas, forming a block copolymer layer on the first electrode and the pixel defining layer, patterning the block copolymer layer, etching the pixel defining layer by using the patterned block copolymer layer as a mask, such that an uneven pixel defining layer with a plurality of defining layer grooves is formed, and forming a light emitting layer on the first electrode and the uneven pixel defining layer.

CROSS-REFERENCE TO RELATED APPLICATION

Korean Patent Application No. 10-2014-0170666, filed on Dec. 2, 2014, inthe Korean Intellectual Property Office, and entitled: “Method ForFabricating Display Device And Display Device,” is incorporated byreference herein in its entirety.

BACKGROUND

1. Field

The present disclosure herein relates to a method for fabricating adisplay device and a display device, and more particularly, to a methodfor fabricating a display device, which is capable of improving displayquality, and a display device.

2. Description of the Related Art

Flat display devices may be classified into light-emitting type displaydevices and light-receiving type display devices. The light-emittingtype display devices include, e.g., flat cathode ray tube (FCRT)displays, plasma display panels (PDPs), and organic light emitting diode(OLED) displays.

For example, the OLED display is an emissive display device and has awide viewing angle, excellent contrast, and fast response speed.Accordingly, since the OLED display is implemented in mobile devices,e.g., a digital camera, a video camera, a portable information terminal,a smart phone, an ultra slim notebook computer, a tablet personalcomputer, and a flexible display device or in large scaleelectrical/electronic products, e.g., an ultra thin television, itreceives great attentions.

The OLED display may realize colors by using a principle in which holesand electrons, which are injected into first and second electrodes, arerecombined with each other to emit light. That is, when excitons, inwhich the injected holes and electrons are combined with each other,return from an excited state to a ground state, light may be emitted.

SUMMARY

Embodiments provide methods for fabricating a display device, includingforming a thin film transistor on a base substrate, forming a firstelectrode connected to the thin film transistor, forming a pixeldefining layer overlapping a portion of the first electrode, such thatthe pixel defining layer exposes a portion of the first electrode andpartitions pixel areas, forming a block copolymer layer on the firstelectrode and the pixel defining layer, patterning the block copolymerlayer, etching the pixel defining layer by using the patterned blockcopolymer layer as a mask, such that an uneven pixel defining layer witha plurality of defining layer grooves is formed, and forming a lightemitting layer on the first electrode and the uneven pixel defininglayer.

In some embodiments, the forming of the uneven pixel defining layer mayinclude forming the uneven pixel defining layer so that the defininglayer grooves are formed to be spaced a predetermined interval from eachother.

In other embodiments, the forming of the uneven pixel defining layer mayinclude forming the uneven pixel defining layer so that the defininglayer grooves have a uniform depth.

In still other embodiments, the forming of the uneven pixel defininglayer may include forming the uneven pixel defining layer so that thedefining layer grooves are formed in a top surface of the uneven pixeldefining layer and are not formed in a bottom surface of the unevenpixel defining layer.

In even other embodiments, the forming of the uneven pixel defininglayer may include: patterning the block copolymer layer to form a blockcopolymer pattern; and etching the pixel defining layer by using theblock copolymer pattern as a mask to form the uneven pixel defininglayer having the defining layer grooves.

In yet other embodiments, the forming of the block copolymer pattern maybe performed by providing ozone, oxygen plasma, and UV.

In further embodiments, the forming of the block copolymer layer may beperformed by using a block copolymer including first repeating units andsecond repeating units different from the first repeating units.

In still further embodiments, the forming of the block copolymer patternmay include: rearranging the first repeating units and the secondrepeating units to form a self-assembly structure in which the firstrepeating units and the second repeating units are alternately arranged;and removing the first repeating units to form the block copolymerpattern.

In even further embodiments, the forming of the self-assembly structuremay be performed through thermal processing or solvent annealing.

In yet further embodiments, in the forming of the self-assemblystructure, the block copolymer may be self-assembled with a sphere,cylinder, lamellar, gyroid, or hexagonal perforated cylinder (HPL)structure.

In much further embodiments, the forming of the uneven pixel defininglayer may include: etching the pixel defining layer by using the secondrepeating units as a mask; and removing the second repeating units.

In still much further embodiments, the etching of the pixel defininglayer may be performed so that the pixel defining layer is etched, andthe first electrode is not etched.

In even much further embodiments, the removing of the second repeatingunits may include removing the second repeating units disposed on thefirst electrode and the uneven pixel defining layer.

In yet much further embodiments, the forming of the uneven pixeldefining layer may include exposing the portion of the first electrode.

In much still further embodiments, the forming of the first electrodemay be performed so that the first electrode does not have grooves.

In even still further embodiments, the methods may further includeforming a second electrode on the uneven pixel defining layer and thelight emitting layer. The second electrode may include a uneven secondelectrode having electrode grooves and a second even electrode extendingfrom the second even electrode and which does not have the electrodegrooves.

In other embodiments, display devices include a base substrate; and aplurality of pixels, wherein at least one of the pixels includes a thinfilm transistor disposed on the base substrate; a first electrodeconnected to the thin film transistor; an uneven pixel defining layerthat overlaps a portion of the first electrode and has a plurality ofdefining layer grooves; a light emitting layer disposed on the firstelectrode and the uneven pixel defining layer; and a second electrodeincluding a uneven second electrode having electrode grooves and asecond even electrode extending from the uneven second electrode andwhich does not have the electrode grooves, the second electrode beingdisposed on the light emitting layer.

In some embodiments, the first electrode may not have grooves.

In other embodiments, the defining layer grooves may be defined in a topsurface of the uneven pixel defining layer and may not be defined in abottom surface of the uneven pixel defining layer.

In still other embodiments, the defining layer grooves may be only onsurfaces of the pixel defining layer facing the second electrode, thedefining layer grooves being spaced apart from each other and having apredetermined depth in the pixel defining layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of ordinary skill in the art bydescribing in detail exemplary embodiments with reference to theattached drawings, in which:

FIG. 1 illustrates a schematic perspective view of a display deviceaccording to an embodiment;

FIG. 2 illustrates a circuit view of one of the pixels in the displaydevice according to an embodiment;

FIG. 3 illustrates a plan view of one of the pixels in the displaydevice according to an embodiment;

FIG. 4 illustrates a schematic cross-sectional view taken along lineI-I′ of FIG. 3;

FIG. 5 illustrates a schematic flowchart of a method for fabricating adisplay device according to an embodiment;

FIGS. 6A to 6G and 6I illustrate cross-sectional views of stages in amethod for fabricating a display device according to an embodiment; and

FIG. 6H illustrates a schematic perspective view of the display devicein FIG. 6G.

DETAILED DESCRIPTION

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey exemplary implementations to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. It will also be understood thatwhen a layer or element is referred to as being “on” another layer orsubstrate, it can be directly on the other layer or substrate, orintervening layers may also be present. In addition, it will also beunderstood that when a layer is referred to as being “between” twolayers, it can be the only layer between the two layers, or one or moreintervening layers may also be present. Like reference numerals refer tolike elements throughout.

It will be understood that although the terms “first” and “second” areused herein to describe various elements, these elements should not belimited by these terms. The terms are only used to distinguish onecomponent from other components. For example, a first element referredto as a first element in one embodiment can be referred to as a secondelement in another embodiment. The terms of a singular form may includeplural forms unless referred to the contrary.

The meaning of ‘include’ or ‘comprise’ specifies a property, a region, afixed number, a step, a process, an element and/or a component but doesnot exclude other properties, regions, fixed numbers, steps, processes,elements and/or components. In the specification, it will be understoodthat when a layer (or film), a region, or a plate is referred to asbeing ‘on’ another layer, region, or plate, it can be directly on theother layer, region, or plate, or intervening layers, regions, or platesmay also be present. On the contrary to this, it will be understood thatwhen a layer (or film), a region, or a plate is referred to as being‘under’ another layer, region, or plate, it can be directly under theother layer (or film), region, or plate, or intervening layers, regions,or plates may also be present.

FIG. 1 illustrates a schematic perspective view of a display device 10according to an embodiment.

Referring to FIG. 1, the display device 10 according to an embodimentmay include a display area DA and a non-display area NDA. An image isdisplayed on the display area DA. When viewed in a thickness direction,e.g., in the DR3 direction in FIG. 1, of the display device 10, thedisplay area DA may have an approximately rectangular shape, but is notlimited thereto.

The display area DA includes a plurality of pixel areas PA. Theplurality of pixel areas PA may be arrayed in a matrix form. Theplurality of pixel areas PA may be defined by an uneven pixel defininglayer (B-PDL in FIG. 4). A plurality of pixels (PX in FIG. 2) may bedisposed on the plurality of pixel areas PA, respectively.

An image is not displayed on the non-display area NDA. For example, thenon-display area may surround the display area DA.

FIG. 2 illustrates a circuit diagram of one of the pixels PX in thedisplay device 10. FIG. 3 illustrates a plan view of one of the pixelsPX in the display device 10, and FIG. 4 illustrates a schematiccross-sectional view taken along line I-I′ of FIG. 3.

Referring to FIGS. 2 to 4, each of the pixels PX includes a wiring unitconstituted by a gate line GL, a data line DL, and a driving voltageline DVL, thin film transistors TFT1 and TFT2 connected to the wiringunit, an organic emitting light device OEL connected to the thin filmtransistors TFT1 and TFT2, and a capacitor Cst.

Each of the pixels PX may emit light having a specific color, e.g., oneof red light, green light, and blue light. The color of emitted light isnot limited to the above-described light. For example, the color ofemitted light may further include, e.g., cyan light, magenta light, andyellow light.

The gate line GL extends in a first direction, e.g., a DR1 direction inFIGS. 1 and 3. The data line DL extends in a second direction, e.g., aDR2 direction in FIGS. 1 and 3, that crosses the gate line GL. Thedriving voltage line DVL extends in a substantially same direction asthe data line DL, e.g., in the second direction DR2 of FIG. 1. The gateline GL transmits a scanning signal into the thin film transistors TFT1and TFT2, the data line DL transmits a data signal into the thin filmtransistors TFT1 and TFT2, and the driving voltage line DVL provides adriving voltage into the thin film transistors TFT1 and TFT2.

The thin film transistors TFT1 and TFT2 may include a driving thin filmtransistor TFT2 for controlling the organic light emitting device OEL,and a switching thin film transistor TFT1 for switching the driving thinfilm transistor TFT2. Each of the pixels PX includes the two thin filmtransistors TFT1 and TFT2 in an embodiment, but is not limited thereto.For example, each of the pixels PX may include one thin film transistorand capacitor or may include at least three thin film transistors and atleast two capacitors.

Referring to FIG. 3, the switching thin film transistor TFT1 includes afirst gate electrode GE1, a first source electrode SE1, and a firstdrain electrode DE1. The first gate electrode GE1 is connected to thegate line GL, and the first source electrode SE1 is connected to thedata line DL. The first drain electrode DE1 is connected to a firstcommon electrode CE1 by a fifth contact hole CH5. The switching thinfilm transistor TFT1 transmits the data signal applied into the dataline DL into the driving thin film transistor TFT2 according to thescanning signal applied into the gate line GL.

The driving thin film transistor TFT2 includes a second gate electrodeGE2, a second source electrode SE2, and a second drain electrode DE2.The second gate electrode GE2 is connected to the first common electrodeCE1. The second source electrode SE2 is connected to the driving voltageline DVL. The second drain electrode DE2 is connected to the firstelectrode EL1 by a third contact hole CH3.

The organic light emitting device OEL is disposed between the firstelectrode EL1 and the second electrode EL2. The first electrode EU isconnected to the second drain electrode DE2 of the driving thin filmtransistor TFT2. When a common voltage is applied to the secondelectrode EL2, a light emitting layer EML emits blue light according toan output signal of the driving thin film transistor TFT2 to display animage. The organic light emitting device OEL, the first electrode EL1,and the second electrode EL2 will be described below in more detail.

The capacitor Cst is connected between the second gate electrode GE2 andthe second source electrode SE2 of the driving thin film transistor TFT2to charge and maintain the data signal inputted into the second gateelectrode GE2 of the driving thin film transistor TFT2. The capacitorCst may include the first common electrode CE1 connected to the firstdrain electrode DE1 by a sixth contact hole CH6 and a second commonelectrode CE2 connected to the driving voltage line DVL.

Referring to FIGS. 3 and 4, the display device 10 according to anembodiment may include a base substrate BS, on which the thin filmtransistor and the organic light emitting device OEL are stacked. Thebase substrate BS may be formed of any suitable material. For example,the base substrate BS may be formed of an insulating material, e.g.,glass, plastic, crystal. An organic polymer for forming the basesubstrate BS may include, e.g., polyethylene terephthalate (PET),polyethylene naphthalate (PEN), polyimide, and polyether sulfone. Thebase substrate BS may be selected in consideration of mechanicalstrength, thermal stability, transparency, surface roughness,tractability, waterproofing property, and the like.

A substrate buffer layer may be disposed on the base substrate BS. Thesubstrate buffer layer may prevent impurities from being diffused intothe switching thin film transistor TFT1 and the driving thin filmtransistor TFT2. The substrate buffer layer may be formed of, e.g.,SiN_(x), SiO_(x), or SiO_(x)N_(y). Also, the substrate buffer layer maybe omitted according to the material and process conditions of the basesubstrate BS.

A first semiconductor layer SM1 and a second semiconductor layer SM2 aredisposed on the base substrate BS. Each of the first and secondsemiconductor layers SM1 and SM2 is formed of a semiconductor material.Also, the first and second semiconductor layers SM1 and SM2 may functionas active layers of the switching and driving thin film transistors TFT1and TFT2, respectively. Each of the first and second semiconductorlayers SM1 and SM2 includes a source area SA, a drain area DA, and achannel area CA disposed between the source area SA and the drain areaDA. Each of the first and second semiconductor layers SM1 and SM2 may beformed of one of an inorganic semiconductor and organic semiconductor.The source area SA and the drain area DA may be doped with n-typeimpurities or p-type impurities.

A gate insulation layer GI is disposed on the first and secondsemiconductor layers SM1 and SM2. The gate insulation layer GI coversthe first and second semiconductor layers SM1 and SM2. The gateinsulation layer GI may be formed of an organic insulation material orinorganic insulation material.

First and second gate electrode GE1 and GE2 are disposed on the gateinsulation layer GI. Each of the first and second gate electrodes GE1and GE2 covers an area corresponding to the channel area CA of each ofthe first and second semiconductor layers SM1 and SM2.

An interlayer dielectric IL is disposed on the first and second gateelectrodes GE1 and GE2. The interlayer dielectric IL covers the firstand second gate electrodes GE1 and GE2. The interlayer dielectric IL maybe formed of an organic insulating material or inorganic insulatingmaterial.

The first source and drain electrodes SE1 and DE1 and the second sourceand drain electrodes SE2 and DE2 are disposed on the interlayerdielectric IL. The second drain electrode DE2 contacts the drain area DAof the second semiconductor layer SM2 by a first contact hole CH1defined in the gate insulation layer GI and the interlayer dielectricIL, and the second source electrode SE2 contacts the source area SA ofthe second semiconductor layer SM2 by a second contact hole Ch2 definedin the gate insulation layer GI and the interlayer dielectric IL. Thefirst source electrode SE1 contacts a source area of the firstsemiconductor layer SM1 by a fourth contact hole CH4 defined in the gateinsulation layer GI and the interlayer dielectric IL, and the firstdrain electrode DE1 contacts a drain area of the first semiconductorlayer SM1 by a fifth contact hole CH5 defined in the gate insulationlayer GI and the interlayer dielectric IL.

A passivation layer PL is disposed on the first source and drainelectrodes SE1 and DE1 and the second source and drain electrodes SE2and DE2. The passivation layer PL may function as a protection layer forprotecting the switching thin film transistor TFT1 and the driving thinfilm transistor TFT 2 and also function as a planarization layer forplanarizing top surfaces of the switching thin film transistor TFT1 andthe driving thin film transistor TFT 2.

The first electrode EL1 is disposed on the passivation layer PL. Thefirst electrode EU may not have grooves.

For example, the first electrode EU may be a pixel electrode or positiveelectrode. The first electrode EL1 is connected to the driving thin filmtransistor TFT2. The first electrode EL1 is connected to the seconddrain electrode DE2 of the driving thin film transistor TFT2 through thethird contact hole CH3 defined in the passivation layer PL.

The first electrode EU may be a transmissive electrode, a transflectiveelectrode, or a reflective electrode. When the first electrode EL1 isthe transmissive electrode, the first electrode EL1 may be formed ofmetal oxide, for example, indium tin oxide (ITO), indium zinc oxide(IZO), zinc oxide (ZnO), or indium tin zinc oxide (ITZO). When the firstelectrode EL1 is the transflective or reflective electrode, the firstelectrode EL1 may be formed of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr,or a metal mixture.

The first electrode EL1 may have a single layer structure formed oftransparent metal oxide or metal or a multi-layered structure includinga plurality of layers. For example, the first electrode EL1 may have asingle layer structure of ITO, Ag, or metal mixture, e.g., a mixture ofAg and Mg, a two-layered structure of ITO/Mg or ITO/MgF, or athree-layered structure of ITO/Ag/ITO, but is not limited thereto.

The pixel areas PA (FIG. 1) are partitioned on the passivation PL tocorrespond to the pixels PX, respectively. Also, the uneven pixeldefining layer B_PDL having a plurality of defining layer grooves H1 andH2 is disposed on the passivation layer PL. The defining layer groovesH1 and H2 include top surface defining layer grooves H1 defined in a topsurface of the uneven pixel defining layer B_PDL, and side surfacedefining layer grooves H2 defined in a side surface of the uneven pixeldefining layer B_PDL. The defining layer grooves H1 and H2 are notdefined in a bottom surface of the uneven pixel defining layer B_PDL.The defining layer grooves H1 and H2 may be formed by etching the pixeldefining layer PDL (FIG. 6B) by using a portion of a block copolymerlayer BCPL (FIG. 6C) disposed on the pixel defining layer PDL (FIG. 6B)as a mask, as will be discussed in more detail below.

If defining layer grooves are formed by using a general photolithographyprocess, it may be difficult to form grooves with a fine structurehaving a size similar to that of a molecule. However, in the displaydevice according to an embodiment, the uneven pixel defining layer B_PDLhas fine defining layer grooves, each of which has a size similar tothat of a molecule, by using the block copolymer BCPL. Also, the unevenpixel defining layer B_PDL having the defining layer grooves that arespaced a predetermined interval from each other may be formed through arelatively simple process.

Referring back to FIG. 4, the uneven pixel defining layer B_PDL exposesa top surface of the first electrode EL1 and protrudes from the basesubstrate BS along a circumference of each of the pixels PX. The unevenpixel defining layer B_PDL may overlap a portion of the first electrodeEL1.

The uneven pixel defining layer B_PDL may include, but is not limitedthereto, at least one of a polymer and a metal-fluorine ion compound.For example, the uneven pixel defining layer B_PDL may be formed of atleast one of polyimide, LiF, BaF₂, and CsF. If the metal-fluorine ioncompound has a predetermined thickness, the metal-fluorine ion compoundmay have an insulating property. For example, the uneven pixel defininglayer B_PDL may have a thickness of about 0.1 μm to about 10 μm

The organic light emitting device OEL is disposed on the pixel area PA(FIG. 1) that is surrounded by the uneven pixel defining layer B_PDL.The organic light emitting device OEL is disposed between the firstelectrode EU and the second electrode EL2. The organic light emittingdevice OEL may include an organic layer. The organic layer may bedisposed on the first electrode EL1. The organic layer includes thelight emitting layer EML. The organic layer may further include a holetransport area HTA and an electron transport area ETA.

The hole transport area HTA may be disposed on the first electrode EL1and the uneven pixel defining layer B_PDL. The hole transport area HTAmay contact the uneven pixel defining layer B_PDL. For example, the holetransport area HTA may contact the side surface defining layer groves H2defined in the side surface of the uneven pixel defining layer B_PDL.The hole transport area HTA may include protrusions coupled to the sidesurface defining layer grooves H2.

The hole transport area HTA may include at least one of a hole injectionlayer, a hole transport layer, a buffer layer, and an electron stoplayer, but is not limited thereto. The hole transport area HTA may havea single layer structure formed of a single material, a single layerstructure formed of materials different from each other, or amulti-layered structure including a plurality of layers formed ofmaterials different from each other.

For example, the hole transport area HTA may have a single layerstructure formed of a plurality of different materials or a structure ofthe hole injection layer/the hole transport layer, the hole injectionlayer/the hole transport layer/the buffer layer, the hole injectionlayer/the buffer layer, the hole transport layer/the buffer layer, orthe hole injection layer/the hole transport layer/the electron stoplayer, which are successively stacked from the first electrode EL1, butis not limited thereto. The hole transport area HTA may be formed byusing various methods, e.g., a vacuum deposition method, a spin coatingmethod, a casting method, a Langmuir-Blodgett (LB) method, an injectprinting method, a laser printing method, and a laser induced thermalimaging (LITI) method.

When the hole transport area HTA includes the hole injection layer, thehole transport area HTA may include a phthalocyanine compound, e.g.,copper phthalocyanine,N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4′-diamine(DNTPD), 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine(m-MTDATA), 4,4′4″-Tris(N,N-diphenylamino)triphenylamine (TDATA),4,4′,4″-tris{N,-(2-naphthyl)-N-phenylamino}-triphenylamine (2TNATA),poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate (PEDOT/PSS),polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA), polyaniline/camphorsulfonicacid (PANI/CSA), and polyaniline/poly(4-styrenesulfonate)(PANI/PSS), but is not limited thereto.

When the hole transport area HTA includes the hole transport layer, thehole transport area HTA may include a carbazole-based derivative, e.g.,N-phenylcarbazole and polyvinylcarbazole, a fluorine-based derivative, atriphenylamine-based derivative such asN,N-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine (TPD)and 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (NPB), and4,4′-Cyclohexylidene bis[N,N-bis(4-methylphenyl)benzenamine] (TAPC), butis not limited thereto.

The hole transport area HTA may have a thickness of about 100 Å to about10,000 Å, e.g., about 100 Å to about 1,000 Å. When the hole transportarea HTA includes both the hole injection layer and the hole transportlayer, the hole injection layer may have a thickness of about 100 Å toabout 10,000 Å, e.g., about 100 Å to about 1,000 Å, and the holetransport layer may have a thickness of about 50 Å to about 2,000 Å,e.g., about 100 Å to about 1,500 Å. When each of the hole transport areaHTA, the hole injection layer, and the hole transport layer has athickness within the above-described range, satisfactory hole transportcharacteristics may be achieved without substantially increasing indriving voltage.

The hole transport area HTA may further include a charge generatingmaterial in addition to the above-described materials to improveconductivity. The charge generating material may be uniformly ornon-uniformly dispersed into the hole transport area HTA. For example,the charge generating material may be a p-dopant. The p-dopant may beone of a quinone derivative, a metal oxide derivative, acyano-containing compound, but is not limited thereto. For example,according to a non-limiting example, the p-dopant may include a quininederivative, e.g., tetracyanoquinodimethane (TCNQ) and2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F4-TCNQ), and metal oxide,e.g., tungsten oxide and molybdenum oxide, but is not limited thereto.

As described above, the hole transport area HTA may further include atleast one of the buffer layer and the electron stop layer, in additionto the hole injection layer and the hole transport layer, but is notlimited thereto. The buffer layer may compensate an optical resonancedistance according to a wavelength of light emitted from the lightemitting layer EML to improve light emission efficiency. A material thatis capable of being contained in the hole transport area HTA may be usedas a material to be contained in the buffer layer. The electron stoplayer may be a layer for preventing electrons from being injected fromthe electron transport area ETA.

The light emitting layer EML may be disposed on the first electrode EL1.The light emitting layer EML may be disposed on the hole transport areaHTA.

The light emitting layer EML may contact the hole transport area HTA andthe uneven pixel defining layer B_PDL. For example, the light emittinglayer EML may contact the side surface defining layer groves H2 definedin the side surface of the uneven pixel defining layer B_PDL. The lightemitting layer EML may include protrusions coupled to the side surfacedefining layer grooves H2. Although not shown, the light emitting layerEML may extend to contact top surface defining layer grooves H1 disposedon the top surface of the uneven pixel defining layer B_PDL.

The light emitting layer EML may have a single layer structure formed ofa single material, a single layer structure formed of materialsdifferent from each other, or a multi-layered structure including aplurality of layers formed of materials different from each other. Thelight emitting layer EML may be formed by using various methods, e.g., avacuum deposition method, a spin coating method, a casting method, aLangmuir-Blodgett (LB) method, an inject printing method, a laserprinting method, and a laser induced thermal imaging (LITI) method.

The light emitting layer EML may be any suitable material, e.g., thelight emitting layer EML may be formed of materials that emit red,green, and blue colors. Alternatively, the light emitting layer mayinclude a phosphor material and a fluorescent material. Also, the lightemitting layer EML may include host or dopant.

The host may be any suitable material. For example, the host may beformed of tris(8-hydroxyquinolino)aluminum (Alq₃),4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP), poly(n-vinylcabazole (PVK),9,10-di(naphthalene-2-yl)anthracene (ADN),4,4′,4″-Tris(carbazol-9-yl)-triphenylamine (TCTA),1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi),3-tert-butyl-9,10-di(naphth-2-yl)anthracene (TBADN), distyrylarylene(DSA), 4,4′-bis(9-carbazolyl)-2,2′-dimethyl-biphenyl (CDBP), or2-Methyl-9,10-bis(naphthalen-2-yl)anthracene (MADNP).

When the light emitting layer EML emits red light, the light emittinglayer EML may include, for example, a phosphor material includingtris(dibenzoylmethanato)phenanthoroline europium (PBD:Eu(DBM)₃(Phen))and perylene. When the light emitting layer EML emits the red light, thedopant contained in the light emitting layer EML may be, e.g., a metalcomplex or an organometallic complex such asbis(1-phenylisoquinoline)acetylacetonate iridium (PIQIr(acac)),bis(1-phenylquinoline)acetylacetonate iridium (PQIr(acac)),PQIr(tris(1-phenylquinoline)iridium), octaethylporphyrin platinum(PtOEP).

When the light emitting layer EML emits green light, the light emittinglayer EML may include, e.g., a fluorescent material includingAlq₃(tris(8-hydroxyquinolino)aluminum. When the light emitting layer EMLemits the green light, the dopant contained in the light emitting layerEML may be selected from, for example, a metal complex or organometalliccomplex such as Ir(ppy)₃(fac-tris(2-phenylpyridine)iridium.

When the light emitting layer EML emits blue light, the light emittinglayer EML may include, e.g., a phosphor material including at least oneof spiro-DPVBi, spiro-6P, distyryl-benzene (DSB), distyryl-arylene(DSA), polyfluorene (PFO)-based polymer or poly(p-phenylene vinylene(PPV)-based polymer. When the light emitting layer EML emits the bluelight, the dopant contained in the light emitting layer EML may be,e.g., a metal complex or an organometallic complex, e.g.,(4,6-F₂ppy)₂Irpic.

As described above, the organic layer may further include the electronhole transport area ETA. The electron transport area ETA may be disposedon the first electrode EL1 and the uneven pixel defining layer B_PDL.The electron transport area ETA may be disposed on the light emittinglayer EML.

The electron transport area ETA may contact the light emitting layer EMLand the uneven pixel defining layer B_PDL. For example, the electrontransport area ETA may contact the side surface defining layer groves H2defined in the side surface of the uneven pixel defining layer B_PDL.The electron transport area ETA may include protrusions coupled to theside surface defining layer grooves H2.

The electron transport area ETA may include at least one of a hole stoplayer, an electron transport layer, and an electron injection layer, butis not limited thereto. For example, the electron transport area ETA mayhave a structure of the electron transport layer/the electron injectionlayer or the hole stop layer/the electron transport layer/the electroninjection layer or a single layer structure in which at least two layersof the above-described layers are combined with each other, but is notlimited thereto. The electron transport area ETA may be formed by usingvarious methods, e.g., a vacuum deposition method, a spin coatingmethod, a casting method, a Langmuir-Blodgett (LB) method, an injectprinting method, a laser printing method, and a laser induced thermalimaging (LITI) method.

When the electron transport area ETA includes the electron transportlayer, the electron transport area ETA may includeTris(8-hydroxyquinolinato)aluminum (Alq₃),1,3,5-Tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi),2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP),4,7-Diphenyl-1,10-phenanthroline (Bphen),3-(4-Biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ),4-(Naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ),2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD),Bis(2-methyl-8-quinolinolato-N1,O8)-(1,1′-Biphenyl-4-olato)aluminum(BAlq), berylliumbis(benzoquinolin-10-olate (Bebq₂),9,10-di(naphthalene-2-yl)anthracene (ADN), and a mixture thereof, but isnot limited thereto. The electron transport area ETA may have athickness of about 100 Å to about 1,000 Å, e.g., about 150 Å to about500 Å. When the electron transport layer has a thickness within theabove-described range, satisfactory electron transport characteristicsmay be achieved without substantially increasing in driving voltage.

When the electron transport area ETA includes the electron injectionlayer, the electron transport area ETA may be formed of a lanthanummetal, e.g., at least one of LiF, Lithium quinolate (LiQ), Li₂O, BaO,NaCl, CsF, and Yb, or of a metal halide, e.g., at least one of RbCl andRbI. The electron injection layer may be formed of a mixture of thematerial for the electron transport material and an organo metal salt.The organo metal salt may be a material having an energy band gap ofabout 4 eV or more. For example, the organo metal salt may include metalacetate, metal benzoate, metal acetoacetate, metal acetylacetonate ormetal stearate. The electron injection layer may have a thickness ofabout 1 Å to about 100 Å, e.g., about 3 Å to about 90 Å. When theelectron injection layer has a thickness within the above-describedrange, satisfactory electron injection characteristics may be achievedwithout substantially increasing in driving voltage.

As described above, the electron transport area ETA may include the holestop layer. For example, the hole stop layer may include at least one of2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and4,7-diphenyl-1,10-phenanthroline (Bphen), but is not limited thereto.The hole stop layer may have a thickness of about 20 Å to about 1,000 Å,e.g., about 30 Å to about 300 Å. When the electron stop layer has athickness within the above-described range, satisfactory electron stopcharacteristics may be achieved without substantially increasing indriving voltage.

The second electrode EL2 may be disposed on the first electrode EL1 andthe uneven pixel defining layer B_PDL. The second electrode EL2 may bedisposed on the electron transport area ETA. The second electrode EL2may contact the electron transport area ETA and the top and sidesurfaces of the uneven pixel defining layer B_PDL.

The second electrode EL2 may include electrode grooves H3. The secondelectrode E12 may include an uneven second electrode EL2_B and an evensecond electrode EL2_N. The even second electrode EL2_N may extend fromat least one end of the uneven second electrode EL2_B. The uneven secondelectrode EL2_B includes the electrode grooves H3. For example, theuneven second electrode EL2_B may contact the top surface of the unevenpixel defining layer B_PDL including the defining layer grooves H1 andH2.

The electrode grooves H3 may be spaced a predetermined interval fromeach other. For example, when viewed in the thickness direction DR3 ofthe display device 10 (from the top), the electrode grooves H3 may bedefined to be spaced apart from each other in the first direction DR1and the second direction DR2 crossing the first direction DR1. Theelectrode grooves H3 may have a uniform minimum distance at which theelectrode grooves H3 are spaced apart from each other in the firstdirection DR1. The electrode grooves H3 may have a uniform minimumdistance at which the electrode grooves H3 are spaced apart from eachother in the second direction DR2. The minimum distance at which theelectrode grooves H3 are spaced apart from each other in the firstdirection DR1 and the minimum distance at which the electrode grooves H3are spaced apart from each other in the second direction DR2 may be thesame or different from each other. The electrode grooves H3 may have auniform depth. For example, the electrode grooves H3 may have a uniformdepth in the thickness direction DR3 of the display device 10.

The even second electrode EL2_N may not include the electrode groovesH3. For example, the second even electrode EL2_N may contact the topsurface of the electron transport area ETA.

The second electrode EL2 may be a common electrode or a negativeelectrode. The second electrode EL2 may be a transmissive electrode, atransflective electrode, or a reflective electrode.

When the second electrode EL2 is the transmissive electrode, the secondelectrode EL2 may include, e.g., Li, Ca, LiF/Ca, LiF/Al, Al, Mg, Ag or acompound or mixture (e.g., a mixture of Ag and Mg) thereof. The secondelectrode EL may include an auxiliary electrode. The auxiliary electrodemay include a layer formed by depositing the above-described materialtoward the light emitting layer and transparent metal oxide on thelayer, e.g., indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide(ZnO), or indium tin zinc oxide (ITZO).

When the second electrode EL2 is the transflective electrode or thereflective electrode, the second electrode EL2 may include, e.g., Ag,Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF/Ca, LiF/Al, or acompound or mixture (e.g., a mixture of Ag and Mg) thereof.Alternatively, the second electrode EL2 may have a multi-layeredstructure including a reflective layer or transflective layer and atransparent conductive layer formed of indium tin oxide (ITO), indiumzinc oxide (IZO), zinc oxide (ZnO), or indium tin zinc oxide (ITZO).

When the organic light emitting device OEL is a front light emittingtype organic light emitting device, the first electrode EL1 may be thereflective electrode, and the second electrode EL2 may be thetransmissive electrode or transflective electrode. When the organiclight emitting device OEL is a rear light emitting type organic lightemitting device, the first electrode EL1 may be the transmissiveelectrode or transflective electrode, and the second electrode EL2 maybe the reflective electrode.

An encapsulation layer SL for covering the second electrode EL2 may bedisposed on the second electrode EL2. The encapsulation layer SL mayinclude an organic material or an inorganic material. The encapsulationlayer SL protects the organic light emitting device OEL.

The display device according to an embodiment may include the unevenpixel defining layer with the defining layer grooves to inducecolor-mixing of the light emitted from the light emitting layer in thestacked direction of the plurality of layers and the light emitted fromthe light emitting layer in a lateral direction of the uneven pixeldefining layer. Thus, in the display device according to an embodiment,color change due to the viewing angle may be reduced, and the side lightmay be efficiency utilized to improve light extraction efficiency.

Hereinafter, a method for fabricating the display device according to anembodiment will be described. Hereinafter, different points with respectto the display device according to the foregoing embodiment in FIGS. 1-4will be mainly described, and thus, non-explained portions will bequoted from the display device according to the foregoing embodiment.

FIG. 5 is a schematic flowchart of a method for fabricating a displaydevice according to an embodiment.

Referring to FIGS. 1 to 5, a method for fabricating the display device10 according to an embodiment may include a process (S100) of formingthe thin film transistors TFT1 and TFT2 on the base substrate BS, aprocess (S200) of forming the first electrode EL1 connected to the thinfilm transistors TFT1 and TFT2, a process (S300) of forming the pixeldefining layer PDL that exposes a portion of the first electrode EL1 andpartitions pixel areas PA, a process (S400) of forming the blockcopolymer layer BCPL on the first electrode EL1 and the pixel defininglayer PDL, a process (S500) of patterning the block copolymer layer BCPLand etching the pixel defining layer PDL by using the patterned blockcopolymer layer BCPL as a mask to form the uneven pixel defining layerB_PDL including the plurality of defining layer grooves H1 and H2, and aprocess (S600) of forming a light emitting layer EML on the uneven pixeldefining layer B_PDL.

FIGS. 6A to 6G and 6I illustrate cross-sectional views of stages in amethod for fabricating the display device 10 according to an embodiment.FIG. 6H illustrates a schematic perspective view of the display devicein FIG. 6G.

Referring to FIGS. 1 to 5 and 6A, the base substrate BS is prepared. Inoperation S100, the thin film transistors TFT1 and TFT2 are formed onthe base substrate BS, followed by covering of the thin film transistorsTFT1 and TFT2 by the passivation layer PL to define a substrate SUB. Inoperation S200, the first electrode EU is formed on the substrate SUBabove the thin film transistors TFT1 and TFT2. The first electrode EL1may not have grooves.

Referring to FIGS. 1 to 5 and 6B, in operation S300, a pixel defininglayer PDL exposing a portion of the first electrode EL1 and partitioningpixel areas is formed on the substrate SUB. The pixel defining layer PDLoverlaps a portion of the first electrode EU. The pixel defining layerPDL may include, but is not limited thereof, at least one of a polymerand a metal-fluorine ion compound. For example, the pixel defining layerPDL may be formed of one metal-fluorine ion compound of polyimide, LiF,BaF₂, and CsF. If the metal-fluorine ion compound has a predeterminedthickness, the metal-fluorine ion compound may have an insulatingproperty. For example, the pixel defining layer PDL may have a thicknessof about 0.1 μm to about 10 μm.

Oxygen plasma processing may be performed on the pixel defining layerPDL. When the oxygen plasma processing is performed, an OH functionalgroup may be generated on the pixel defining layer PDL.

Neutral layer processing and thermal processing may be performed on thepixel defining layer PDL on which the oxygen plasma processing isperformed. The neutral layer processing and thermal processing may beperformed on the pixel defining layer PDL without performing the oxygenplasma processing.

Referring to FIGS. 1 to 5 and 6C, in operation S400, the block copolymerlayer BCPL is formed, e.g., conformally, on the first electrode EL1 andthe pixel defining layer PDL. In operation (S400), the block copolymerlayer BCPL may be any suitable material, e.g., at least one blockcopolymer of a polystyrene-polymethylmethacrylate copolymer, apolybutadiene-polybutylmethacrylate copolymer, apolybutadiene-polydimethylsiloxane copolymer, apolybutadienepolymethylmethacrylate copolymer, apolybutadiene-polyvinylpyridine copolymer, apolybutylacrylate-polymethylmethacrylate copolymer,polybutylacrylate-polyvinylpyridine copolymer, apolyisoprene-polyvinylpyridine copolymer, apolyisoprenepolymethylmethacrylate copolymer, apolyhexylacrylate-polyvinylpyridine copolymer, apolyisobutylene-polybutylmethacrylate copolymer, apolyisobutylene-polymethylmethacrylate copolymer, apolyisobutylene-polybutylmethacrylate copolymer, apolyisobutylenepolydimethylsiloxane copolymer, apolybutylmethacrylatepolybutylacrylate copolymer, apolyethylethylene-polymethylmethacrylate copolymer, apolystyrene-polybutylmethacrylate copolymer, a polystyrene-polybutadienecopolymer, a polystyrene-polyisoprene copolymer, apolystyrene-polydimethylsiloxane copolymer, apolystyrene-polyvinylpyridine copolymer, apolyethylethylene-polyvinylpyridine copolymer, apolyethylene-polyvinylpyridine copolymer, apolyvinylpyridinepolymethylmethacrylate copolymer, apolyethyleneoxide-polyisoprene copolymer, apolyethyleneoxide-polybutadiene copolymer, apolyethyleneoxide-polystyrene copolymer, apolyethyleneoxidepolymethylmethacrylate copolymer, a(polyethyleneoxide-polydimethylsiloxane copolymer, and apolystyrene-polyethyleneoxide copolymer.

The block copolymer may include a linear or branched polymer having amolecular weight of several thousand g/mol to several million g/mol,e.g., about 3,000 g/mol to about 2,000,000 g/mol. The block copolymermay have any suitable shape, e.g., a diblock copolymer in which a firstrepeating unit (see reference symbol R1 of FIG. 6D) and a secondrepeating unit (see reference symbol R2 of FIG. 6D) are covalentlybonded in the form of (first repeating unit)-co-(second repeating unit)or a triblock copolymer in which the first repeating unit and the secondrepeating unit are covalently bonded in the form of (first repeatingunit)-co-(second repeating unit)-co-(first repeating unit). In anotherexample, the block copolymer may include a triblock copolymer in whichthe first repeating unit, the second repeating unit, and a thirdrepeating unit are covalently bonded in the form of (first repeatingunit)-co-(second repeating unit)-co-(third repeating unit). However,embodiments are not limited thereto. For example, the block copolymermay include a multi-component block copolymer having various forms.

Referring to FIGS. 1 to 5, in operation S500, the block copolymer layerBCPL (FIG. 6C) is patterned, and then the pixel defining layer PDL isetched by using the pattern block copolymer as a mask to form the unevenpixel defining layer B_PDL having the defining layer grooves H1 and H2.In detail, operation S500 may include forming the uneven pixel defininglayer B_PDL by patterning the block copolymer BCPL (of FIG. 6C) to forma block copolymer pattern BCP_P (FIG. 6E), and etching the pixeldefining layer PDL (of FIG. 6C) by using the block copolymer patternBCP_P as a mask to form the uneven pixel defining layer B_PDL having thedefining layer grooves H1 and H2.

The process of forming the block copolymer pattern BCP_P may include aprocess of rearranging the first repeating units (see reference symbolR1 of FIG. 6D) and the second repeating units (see reference symbol R2of FIG. 6D) to form a self-assembly structure (see reference symbolS_BCPL of FIG. 6D), in which the first repeating units (see referencesymbol R1 of FIG. 6D) and the second repeating units (see referencesymbol R2 of FIG. 6D) are alternately arranged, and a process ofremoving the first repeating units (see reference symbol R1 of FIG. 6D)to form the block copolymer pattern (see reference numeral BCP_P of FIG.6E).

In detail, referring to FIGS. 1 to 5 and 6D, the first repeating units(see reference symbol R1 of FIG. 6D) and the second repeating units (seereference symbol R2 of FIG. 6D) may be rearranged to form theself-assembly structure (see reference symbol S_BCPL of FIG. 6D) inwhich the first repeating units (see reference symbol R1 of FIG. 6D) andthe second repeating units (see reference symbol R2 of FIG. 6D) arealternately arranged. In the process of forming the self-assemblystructure S_BCPL, the block copolymer may be self-assembled with variousstructures. For example, the block copolymer may be self-assembled witha sphere, cylinder, lamellar, gyroid, or hexagonal perforated cylinder(HPL) structure. The process of forming the self-assembly structureS_BCPL may be performed in any suitable manner, e.g., through thermalprocessing or solvent annealing.

Referring to FIGS. 1 to 5, 6D, and 6E, the first repeating units R1 areremoved to form the block copolymer pattern BCP_P. For example, theblock copolymer pattern BCP_P may not be etched to form the secondrepeating units R2 remaining on the first electrode EL1 and the pixeldefining layer PDL. The block copolymer pattern BCP_P may be spaced apredetermined interval from each other.

In the process of forming the block copolymer pattern BCP_P, the firstrepeating units R1 may be etched to form the block copolymer patternBCP_P. For example, the first repeating units R1 may be removed by dryetching or wet etching. In the process of forming the block copolymerpattern BCP_P, the process of etching the first repeating units R1 maybe any suitable process, e.g., by providing at least one of ozone,oxygen, plasma, and UV.

Referring to FIGS. 1 to 5 and 6F, the pixel defining layer PDL is etchedby using the second repeating units R2 as a mask. The pixel defininglayer PDL may be etched by using the second repeating units R2 as a maskto form the uneven pixel defining layer B_PDL. In the process of etchingthe pixel defining layer PDL, the pixel defining layer PDL may beetched, and the first electrode EU may not be etched.

Referring to FIGS. 1 to 5, 6G, and 6H, a process of removing the secondrepeating units R2 remaining on the first electrode EL1 and the unevenpixel defining layer B_PDL may be performed. For example, the secondrepeating units R2 may be removed by dry or wet etching. Any suitableprocess for removing the second repeating units R2 maybe sued, e.g.,providing at least one of ozone, oxygen plasma, and UV.

The uneven pixel defining layer B_PDL includes a plurality of defininglayer grooves H1 and H2. The defining layer grooves H1 and H2 includetop surface defining layer grooves H1 defined in a top surface of theuneven pixel defining layer B_PDL, and side surface defining layergrooves H2 defined in a side surface of the uneven pixel defining layerB_PDL. The defining layer grooves H1 and H2 are not defined in a bottomsurface of the uneven pixel defining layer B_PDL.

The defining layer grooves H1 and H2 may be spaced a predeterminedinterval from each other. For example, when viewed in the thicknessdirection DR3 of the display device 10 (from top view), the defininglayer grooves H1 and H2 may be defined to be spaced apart from eachother in the first direction DR1 and the second direction DR2 crossingthe first direction DR1. The defining layer grooves H1 and H2 may have auniform minimum distance P1 in which the defining layer grooves H1 andH2 are spaced apart from each other in the first direction DR1. Thedefining layer grooves H1 and H2 may have a uniform minimum distance P2in which the defining layer grooves H1 and H2 are spaced apart from eachother in the second direction DR1.

For example, each of the minimum distance P1 at which the defining layergrooves H1 and H2 are spaced apart from each other in the firstdirection DR1, and the minimum distance P2 at which the defining layergrooves H1 and H2 are spaced apart from each other in the seconddirection DR2 may be about 5 nm to about 1,000 nm. When each of theminimum distance P1, at which the defining layer grooves H1 and H2 arespaced apart from each other in the first direction DR1, and the minimumdistance P2, at which the defining layer grooves H1 and H2 are spacedapart from each other in the second direction DR2, is about 5 nm orless, it may be difficult to control the process due to the shortdistance between the defining layer grooves H1 and H2. On the otherhand, when each of the minimum distance P1, at which the defining layergrooves H1 and H2 are spaced apart from each other in the firstdirection DR1, and the minimum distance P2, at which the defining layergrooves H1 and H2 are spaced apart from each other in the seconddirection DR2, is greater than about 1,000 nm, it may be difficult tosufficiently induce the color-mixing of the light emitted from the lightemitting layer in the stacked direction of the plurality of layers andthe light emitted from the light emitting layer in the lateral directionof the uneven pixel defining layer due to the long distance between thedefining layer grooves H1 and H2.

Although the minimum distance P1, at which the defining layer grooves H1and H2 are spaced apart from each other in the first direction DR1, andthe minimum distance P2, at which the defining layer grooves H1 and H2are spaced apart from each other in the second direction DR2, are thesame in FIG. 6H, the present disclosure is not limited thereto. Forexample, the minimum distance P1, at which the defining layer grooves H1and H2 are spaced apart from each other in the first direction DR1, andthe minimum distance P2, at which the defining layer grooves H1 and H2are spaced apart from each other in the second direction DR2, may bedifferent from each other.

The defining layer grooves H1 and H2 may have a uniform depth. Forexample, the defining layer grooves H1 and H2 may have a uniform depthin the thickness direction DR3 of the display device 10. The defininglayer grooves H1 and H2 may have a depth of, e.g., about 5 nm to about1,000 nm. When each of the defining layer grooves H1 and H2 has a depthof about 5 nm or less, it may be difficult to control the process due tothe short distance between the defining layer grooves. On the otherhand, when each of the defining layer grooves H1 and H2 has a depthgreater than about 1,000 nm, it may be difficult to sufficiently inducethe color-mixing of the light emitted from the light emitting layer inthe stacked direction of the plurality of layers and the light emittedfrom the light emitting layer in the lateral direction of the unevenpixel defining layer due to the long distance between the defining layergrooves H1 and H2.

If the defining layer grooves are formed by using a generalphotolithography process, it may be difficult to form a fine structurehaving a size similar to that of a molecule. However, in the displaydevice according to an embodiment, the fine defining layer grooves, eachof which has a size similar to that of a molecule, may be formed byusing the block copolymer. Also, the defining layer grooves that aredefined to be spaced a predetermined interval from each other may beformed through a relatively simple process.

Referring to FIGS. 1 to 5 and 6I, in operation S600, the block copolymerlayer BCPL is formed on the first electrode EL1 and the pixel defininglayer PDL. The light emitting layer EML may be disposed on the firstelectrode EL1. The light emitting layer EML may be disposed on the holetransport area HTA.

The light emitting layer EML may contact the uneven pixel defining layerB_PDL. For example, the light emitting layer EML may contact the sidesurface defining layer groves H2 defined in the side surface of theuneven pixel defining layer B_PDL. Although not shown, the lightemitting layer EML may extend to contact top surface defining layergrooves H1 disposed on the top surface of the uneven pixel defininglayer B_PDL.

The method for fabricating the display device 10 according to anembodiment may further include a process of forming a second electrodeEL2 on the uneven pixel defining layer B_PDL and the light emittinglayer EML. The second electrode EL2 may be disposed on the firstelectrode EL1 and the uneven pixel defining layer B_PDL. The secondelectrode EL2 may be disposed on the electron transport area HTAdisposed on the light emitting layer EML.

The second electrode EL2 may include the electrode grooves H3. Thesecond electrode EL2 may include the uneven second electrode EL2_B andthe even second electrode EL2_N. The even second electrode EL2_N mayextend from at least one end of the uneven second electrode EL2_B. Theuneven second electrode EL2_B includes the electrode grooves H3. Forexample, the uneven second electrode may contact the top surface of theuneven pixel defining layer B_PDL including the defining layer groovesH1 and H2.

The electrode grooves H3 may be spaced a predetermined interval fromeach other. For example, when viewed in the thickness direction DR3 ofthe display device 10, the electrode grooves H3 may be defined to bespaced apart from each other in the first direction DR1 and the seconddirection DR2 crossing the first direction DR1. The electrode grooves H3may have a uniform minimum distance in which the electrode grooves H3are spaced apart from each other in the first direction DR1. Theelectrode grooves H3 may have a uniform minimum distance at which theelectrode grooves H3 are spaced apart from each other in the seconddirection DR2. The minimum distance at which the electrode grooves H3are spaced apart from each other in the first direction DR1 and theminimum distance at which the electrode grooves H3 are spaced apart fromeach other in the second direction DR2 may be the same or different fromeach other. The electrode grooves H3 may have a uniform depth in thethickness direction DR3 of the display device 10.

The even second electrode EL2_N may not include the electrode groovesH3. For example, the second even electrode EL2_N may contact the topsurface of the electron transport area ETA.

If the defining layer grooves are formed by using a generalphotolithography process, it may be difficult to form a fine structurehaving a size similar to that of a molecule. However, in the displaydevice according to an embodiment, the uneven pixel defining layerhaving fine defining layer grooves, each of which has a size similar tothat of a molecule, may be formed by using the block copolymer. Also,the defining layer grooves that are defined to be spaced a predeterminedinterval from each other may be formed through a relatively simpleprocess.

The display device and method of fabrication thereof according to anembodiment may include the uneven pixel defining layer with the defininglayer grooves, thereby inducing color-mixing of the light emitted fromthe light emitting layer in the stacked direction of the plurality oflayers and the light emitted from the light emitting layer in a lateraldirection of the uneven pixel defining layer. Thus, in the displaydevice according to an embodiment, a color change due to the viewingangle may be reduced, and the side light may be efficiency utilized toimprove light extraction efficiency. As such, the display deviceaccording to an embodiment may exhibit improved display quality, and themethod for fabricating the display device may be simplified.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

1. A method for fabricating a display device, the method comprising:forming a thin film transistor on a base substrate; forming a firstelectrode connected to the thin film transistor; forming a pixeldefining layer overlapping a portion of the first electrode, such thatthe pixel defining layer exposes a portion of the first electrode andpartitions pixel areas; forming a block copolymer layer on the firstelectrode and the pixel defining layer; patterning the block copolymerlayer; etching the pixel defining layer by using the patterned blockcopolymer layer as a mask, such that an uneven pixel defining layer witha plurality of defining layer grooves is formed; and forming a lightemitting layer on the first electrode and the uneven pixel defininglayer.
 2. The method as claimed in claim 1, wherein forming the unevenpixel defining layer includes forming the defining layer grooves thereinto be spaced a predetermined interval from each other.
 3. The method asclaimed in claim 1, wherein forming the uneven pixel defining layerincludes forming the defining layer grooves therein to have a uniformdepth.
 4. The method as claimed in claim 1, wherein forming the unevenpixel defining layer includes forming the defining layer grooves in atop surface of the uneven pixel defining layer, such that no defininglayer grooves are formed in a bottom surface of the uneven pixeldefining layer.
 5. The method as claimed in claim 1, wherein forming theuneven pixel defining layer includes: patterning the block copolymerlayer to form a block copolymer pattern; and etching the pixel defininglayer by using the block copolymer pattern as a mask to form the unevenpixel defining layer having the defining layer grooves.
 6. The method asclaimed in claim 5, wherein forming the block copolymer pattern isperformed by providing ozone, oxygen plasma, or UV.
 7. The method asclaimed in claim 5, wherein forming the block copolymer layer isperformed by using a block copolymer including first repeating units andsecond repeating units different from the first repeating units.
 8. Themethod as claimed in claim 7, wherein forming the block copolymerpattern includes: rearranging the first repeating units and the secondrepeating units to form a self-assembly structure in which the firstrepeating units and the second repeating units are alternately arranged;and removing the first repeating units to form the block copolymerpattern.
 9. The method as claimed in claim 8, wherein forming theself-assembly structure is performed through thermal processing orsolvent annealing.
 10. The method as claimed in claim 8, wherein, in theforming of the self-assembly structure, the block copolymer isself-assembled with a sphere, a cylinder, a lamellar, a gyroid, or ahexagonal perforated cylinder (HPL) structure.
 11. The method as claimedin claim 8, wherein forming the uneven pixel defining layer includes:etching the pixel defining layer by using the second repeating units asa mask; and removing the second repeating units.
 12. The method asclaimed in claim 11, wherein etching the pixel defining layer includesetching the pixel defining layer without etching the first electrode.13. The method as claimed in claim 11, wherein removing the secondrepeating units includes removing the second repeating units disposed onthe first electrode and the uneven pixel defining layer.
 14. The methodas claimed in claim 1, wherein forming the uneven pixel defining layerincludes exposing the portion of the first electrode.
 15. The method asclaimed in claim 1, wherein forming the first electrode is performed sothat the first electrode does not have grooves.
 16. The method asclaimed in claim 1, further comprising forming a second electrode on theuneven pixel defining layer and the light emitting layer, such that thesecond electrode includes an uneven second electrode with electrodegrooves, and an even second electrode extending from the uneven secondelectrode and having no electrode grooves.
 17. A display device,comprising: a base substrate; and a plurality of pixels on the basesubstrate, at least one pixel of the plurality of pixels including: athin film transistor on the base substrate, a first electrode connectedto the thin film transistor, an uneven pixel defining layer overlappinga portion of the first electrode, the uneven pixel defining layer havinga plurality of defining layer grooves, a light emitting layer on thefirst electrode and the uneven pixel defining layer, and a secondelectrode having an uneven second electrode with electrode grooves, andan even second electrode extending from the uneven second electrode andhaving no electrode grooves, the second electrode being disposed on thelight emitting layer, wherein the uneven pixel defining layer includesside surfaces adjacent an opening overlapping the light emitting layer,the side surfaces including at least a portion of the defining layergrooves.
 18. The display device as claimed in claim 17, wherein thefirst electrode does not have grooves.
 19. The display device as claimedin claim 17, wherein the defining layer grooves are defined in a topsurface of the uneven pixel defining layer and are not defined in abottom surface of the uneven pixel defining layer.
 20. The displaydevice as claimed in claim 17, wherein the defining layer grooves areonly on surfaces of the pixel defining layer facing the secondelectrode, the defining layer grooves being spaced apart from each otherand having a predetermined depth in the pixel defining layer.
 21. Thedisplay device as claimed in claim 17, wherein the pixel defining layerhas substantially flat surfaces between respective pairs of the defininglayer grooves.
 22. The display device as claimed in claim 21, whereinthe flat surfaces extend beyond bottom surfaces of the defining layergrooves.
 23. The display device as claimed in claim 17, wherein thelight emitting layer is on the defining layer grooves and has an unevensurface that substantially conforms to the defining layer grooves.